Luton had no answer to the marauding Norwegian who bagged his eighth City hat-trick before half-time and then scored twice more after the break to kill off a stirring Luton revival.
The 23-year-old Haaland’s first four goals were all created by Kevin De Bruyne. Mateo Kovacic also got on the scoresheet for holders City who are unbeaten in 18 games in all competitions.
Luton did threaten an unlikely comeback when Jordan Clark found the top corner with a sublime effort on the stroke of halftime and netted again early in the second half to make it 3-2. But a strong City side instantly found another gear to cruise into the hat for the last eight.
The only blemish for City, who face Manchester United in the Premier League on Sunday, was an injury to Jack Grealish who was forced off in the opening period.
LUTON TOWN VS MANCHESTER CITY LIVE: FA CUP UPDATES
- Luton Town host FA Cup holders Manchester City in fifth round
- GOAL! Luton 2 Man City 6 (Mateo Kovacic 72)
- GOAL! Luton 2 Man City 5 (Erling Haaland 58)
- GOAL! Luton 2 Man City 4 (Erling Haaland 55)
- GOAL! Luton 2 (Jordan Clark 52) Man City 3
- GOAL! Luton 1 (Jordan Clark 45) Man City 3
- GOAL! Luton 0 Man City 3 (Erling Haaland 40, Hat-trick)
- GOAL! Luton 0 Man City 2 (Erling Haaland 18)
- GOAL! Luton 0 Man City 1 (Erling Haaland 3)
